Study on Fouling Behavior of Simulated EPS Solution

Extracellular polymer substance (EPS) in activated sludge suspension is the main factor of membrane pollution. This study systematically studied the fouling behavior and mechanism of extracellular polymer substance model solutions (BSA, HA, SA). With solutions of different concentrations (BSA, HA, SA) as the feed solution, a series of constant cross-flow filtration experiments were conducted using 0.1 μm PAN microfiltration membrane. The transmembrane pressure (P), fouling resistance (R), and effective area ratio (A/A0) were used to describe membrane fouling. The results show that the fouling mechanism of BSA is pore blocking-cake mechanism. With the increase of concentration, the transmembrane pressure rises faster, the effective area decreases faster, and the fouling becomes more serious. When the concentration of HA is less than 1 g L⁻¹, the fouling mechanism is a single pore-blocking. When the pore-blocking is completed, the available area ratio and resistance no longer change. At high concentration, the fouling mechanism is pore blocking-cake, the available area ratio tends to be stable, and the resistance increase is mainly caused by the cake. When SA concentration is less than 1 g L⁻¹, the fouling mechanism is a single pore-blocking mechanism. When the pore-blocking is completed, the effective area ratio and resistance will not change. The fouling mechanism of SA at high concentration is pore blocking-cake mechanism. The high concentration causes the cake to appear earlier. This study provides an insight for further understanding the fouling behavior and mechanism of EPS solution, which can provide theoretical guidance for practical application.